William Harrison “Jack” Dempsey (“The Manassa Mauler”) (June 24, 1895 – May 31, 1983) was an American boxer who held the world heavyweight title from 1919 to 1926. Dempsey’s aggressive style and exceptional punching power made him one of the most popular boxers in history. Many of his fights set financial and attendance records, including the first million dollar gate. He is listed #10 on The Ring’s list of all-time heavyweights and #7 among its Top 100 Greatest Punchers. He is a member of the International Boxing Hall of Fame.

Dempsey was also something of a cross-trainer; he wrestled in training camp and later took judo lessons. He later wrote a book on this, How to Fight Tough, which dealt with close-quarters combat incorporating boxing, wrestling, and jiujitsu

True to his passion for the sport, Dempsey wrote a book on boxing called Championship Fighting: Explosive Punching and Aggressive Defense, which was published in 1950. The book emphasizes knockout power derived from enabling fast motion from one’s heavy bodyweight. Though no longer in print, Dempsey’s book became and remains the recognized treatise in boxing and has influenced such works from Edwin Haislet and Bruce Lee.